StringLeftAddition.cs

using Waher.Runtime.Inventory;
using Waher.Script.Abstraction.CustomOperators;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Operators.Arithmetics.Custom
{
    public class StringLeftAddition : IBinaryOperator
    {
        public StringLeftAddition()
        {
        }
 
        public Grade Supports(IBinaryOperation Operation)
        {
            if (Operation.Name != "op_Addition")
                return Grade.NotAtAll;
 
            object Left = Operation.Left.AssociatedObjectValue;
            object Right = Operation.Right.AssociatedObjectValue;
 
            if (Left is string && !(Right is string))
                return Grade.Barely;
            else
                return Grade.NotAtAll;
        }
 
        public IElement Evaluate(IBinaryOperation Operation, ScriptNode Node)
        {
            string Left = ScriptNode.ToString(Operation.Left) ?? string.Empty;
            string Right = ScriptNode.ToString(Operation.Right) ?? string.Empty;
 
            return new StringValue(Left + Right);
        }
    }
}